Kant's Critique of Metaphysics

How are synthetic a priori propositions possible? This
question is often times understood to frame the investigations at
issue in Kant's Critique of Pure Reason. In answer to it,
Kant saw fit to divide the question into three: 1) How are the
synthetic a priori propositions of mathematics possible? 2)
How are the synthetic a priori propositions of natural
science possible? Finally, 3) How are the synthetic a priori
propositions of metaphysics possible? In systematic fashion, Kant
responds to each of these questions. The answer to question one is
broadly found in the Transcendental Aesthetic, and the doctrine of the
transcendental ideality of space and time. The answer to question two
is found in the Transcendental Analytic, where Kant seeks to
demonstrate the essential role played by the categories in grounding
the possibility of knowledge and experience. The answer to question
three is found in the Transcendental Dialectic, and it is a
resoundingly blunt conclusion: the synthetic a priori
propositions that characterize metaphysics are not really possible at
all. Metaphysics, that is, is inherently
dialectical. Kant's Critique of Pure Reason is thus as well
known for what it rejects as for what it defends. Thus, in the
Dialectic, Kant turns his attention to the central disciplines of
traditional, rationalist, metaphysics — rational psychology,
rational cosmology, and rational theology. Kant aims to reveal the
errors that plague each of these fields.

Despite the fact that Kant devotes an entirely new section of the
Critique to the branches of special metaphysics, his
criticisms reiterate some of the claims already defended in both the
Transcendental Aesthetic and the Transcendental Analytic. Indeed, two
central teachings from these earlier portions of the Critique
— the transcendental ideality of space and time, and the
critical limitation of all application of the concepts of the
understanding to “appearances” — already carry with
them Kant's rejection of “ontology (metaphysica
generalis).” Accordingly, in the Transcendental
Analytic Kant argues against any attempt to acquire knowledge of
“objects in general” through the formal concepts and
principles of the understanding, taken by themselves alone. In this
connection, Kant denies that the principles or rules of either general
logic (e.g., the principle of contradiction), or those of his own
“transcendental logic” (the pure concepts of the
understanding) by themselves yield knowledge of
objects. These claims follow from Kant's well-known “kind
distinction” between the understanding and sensibility, together
with the view that knowledge requires the cooperation of both
faculties. This position, articulated throughout the Analytic, entails
that independently of their application to intuitions, the concepts
and principles of the understanding are mere forms of thought which
cannot yield knowledge of objects.

For if no intuition could be given corresponding to the
concept, the concept would still be a thought, so far as its form is
concerned, but would be without any object, and no knowledge of
anything would be possible by means of it. So far as I could know,
there would be nothing, and could be nothing, to which my thought
could be applied. B147

We thus find one general complaint about efforts to acquire
metaphysical knowledge: the use of formal concepts and principles, in
abstraction from the sensible conditions under which objects can be
given, cannot yield knowledge. Hence, the “transcendental”
use of the understanding (its use independently of the conditions of
sensibility) is considered by Kant to be dialectical, to involve
erroneous applications of concepts in order to acquire knowledge of
things independently of sensibility/experience. Throughout the
Analytic Kant elaborates on this general view, noting that the
transcendental employment of the understanding, which aims towards
knowledge of things independently of experience (and thus knowledge of
“noumena”), is illicit (cf. A246/B303). It is in this
connection that Kant states, famously, in the Analytic, that
“…the proud name of ontology, which presumes to offer
synthetic a priori cognitions of things in general…
must give way to the more modest title of a transcendental
analytic” (cf. A247/B304). Filling this out, Kant suggests that
to take ourselves to have unmediated intellectual access to objects
(to have “non-sensible” knowledge) correlates with the
assumption that there are non-sensible objects that we can know. To
assume this, however, is to conflate “phenomena” (or
appearances) with “noumena” (or things in themselves). The
failure to draw the distinction between appearances and things in
themselves is the hallmark of all those pernicious systems of thought
that stand under the title of “transcendental
realism.” Kant's transcendental idealism is the remedy for
these.

Kant's rejection of the more specialized branches of metaphysics is in
part grounded in this earlier claim, to wit, that any attempt to apply
the concepts and principles of the understanding independently of the
conditions of sensibility (i.e., any transcendental use of the
understanding) is illicit. Thus, one of Kant's main complaints is that
metaphysicians seek to deduce a priori synthetic knowledge
simply from the unschematized (pure) concepts of the
understanding. The effort to acquire metaphysical knowledge through
concepts alone, however, is doomed to fail, according to Kant, because
(in its simplest formulation) “concepts without intuitions are
empty” (A52/B76).

Although this general charge is certainly a significant part of Kant's
complaint, the story does not stop here. In turning to the specific
disciplines of special metaphysics (those concerning the soul, the
world, and God), Kant devotes a considerable amount of time discussing
the human interests that nevertheless pull us into the thorny
questions and controversies that characterize special
metaphysics. These interests are of two types, and include theoretical
goals of achieving completeness and systematic unity of knowledge, and
practical interests in securing the immortality of the soul, freedom,
and the existence of God. Regardless, Kant tells us that the goals and
interests in question are unavoidable, inevitable, and inherent in the
very nature of human reason. In the Introduction to the Transcendental
Dialectic Kant thus introduces “reason” as the locus of
these metaphysical interests.

The emphasis on reason in this connection is important, and it links
up with the project of Kant's “critique” of pure reason. A
major component of this critique involves illuminating the basis in
reason for our efforts to draw erroneous metaphysical conclusions (to
employ concepts “transcendentally”), despite the fact that
such use has already been shown (in the Transcendental Analytic) to be
illicit. What emerges in the Dialectic is a more complex story, one in
which Kant seeks to disclose and critique the “transcendental
ground” that leads to the misapplications of thought which
characterize the specific metaphysical arguments. In developing the
position that our metaphysical propensities are grounded in the
“very nature of human reason,” Kant (in the Introduction
to the Dialectic) characterizes reason as a capacity for syllogistic
reasoning. This logical function of reason resides in the formal
activity of subsuming propositions under ever more general principles
in order to systematize, unify, and “bring to completion”
the knowledge given through the real use of the understanding
(A306/B363-A308/B365). Kant thus characterizes this activity as one
which seeks “conditions” for every condition. It is
therefore central to this Kantian conception of reason that it is
preoccupied with the “unconditioned.”

The demand for the unconditioned, in turn, is essentially a demand for
ultimate explanation, and links up with the rational prescription to
secure systematic unity and completeness of knowledge. Reason, in
short, is in the business of ultimately accounting for all things. As
Kant formulates this interest of reason in the first
Critique, it is characterized by the logical maxim or precept
thus: “Find for the conditioned knowledge given through the
understanding the unconditioned whereby its unity is brought to
completion” (A308/B364). It is central to Kant's
Dialectic that this requirement for systematic unity and completeness
of knowledge is inherent in the very nature of our reason.
Controversially, he does not take it that this demand for the
unconditioned is something we can dismiss, nor does he take the
interests we have in metaphysics to be merely products of
misguided enthusiasm.

Although the demand for the unconditioned is inherent in the very
nature of our reason, although it is unavoidable and indispensably
necessary, Kant nevertheless does not take it to be without problems
of a unique sort; for the very same demand that guides our rational
scientific inquiries and defines our (human) reason is also the locus
of error that needs to be curbed or prevented. In connection with this
principle, then, Kant also identifies reason as the seat of a unique
kind of error, one that is essentially linked up with metaphysical
propensities, and one which he refers to as “transcendental
illusion [transzendentale Illusion].” Kant identifies
transcendental illusion with the propensity to “take a
subjective necessity of a connection of our concepts…for an
objective necessity in the determination of things in
themselves” (A297/B354). Very generally, Kant's claim is that it
is a peculiar feature of reason that it unavoidably takes its own
subjective interests and principles to hold
“objectively.” And it is this propensity, this
“transcendental illusion,” according to Kant, that paves
the way for metaphysics. Reason plays this role by generating
principles and interests that incite us to defy the limitations of
knowledge already detailed in the Transcendental Analytic. The
Introduction to the Transcendental Dialectic is therefore interesting
for Kant's presentation of reason as a presumably distinct capacity
for cognizing in a way that, as Kant puts it, incites us to tear down
the boundaries already enforced in the Analytic (cf. A296/B352). Kant
refers to this capacity of reason as one that leads to the
specifically transcendent judgments that characterize
metaphysics. Thus, the Transcendental Dialectic is said to be
concerned “to expose the illusion in transcendent
judgments” (A297/B354). Indeed, Dialectic is defined as
“the logic of illusion [Schein]”
(A293/B350).

The central problem is that the above prescription to seek
the unconditioned presents to reason as a metaphysical principle that
tells us that the unconditioned is already given, and is (as
it were) “there” to be found. This problematic principle
is formulated by Kant as follows: “If the conditioned is
given, the absolutely unconditioned… is also given”
(A308/B366). This “supreme principle of pure reason”
provides the background assumption under which the metaphysician
proceeds. These claims set the agenda for Kant's project, which
involves showing not simply that the metaphysical arguments are
fallacious, but also exposing their source in reason's illusions.

Kant has been traditionally taken to be offering a method of avoiding
the insidious “transcendental illusion” that he suggests
gives rise to metaphysics. Read in this way, Kant's Dialectic offers a
criticism not only of the specific arguments of metaphysics, but also
of transcendent, metaphysical (speculative or theoretical)
interests and propensities themselves. This certainly accords
with much in the Dialectic, and specifically with Kant's well-known
claim that knowledge has to be limited to possible experience. Kant,
however, complicates things somewhat by also stating repeatedly that
the illusion that grounds metaphysics (roughly, that the unconditioned
is already given) is unavoidable. Moreover, Kant sometimes suggests
that such illusion is somehow necessary for our epistemological
projects (cf. A645/B673). In essence, Kant argues that the
transcendent ideas and principles of reason do have a positive role to
play in knowledge acquisition, so long as they are construed
“regulatively” and not “constitutively.” He
thus suggests that rather than jettison the ideas of metaphysical
objects (something, it seems, he does not think we are in a position
to do), it is best to identify the proper use and function of these
ideas and principles. This critical reinterpretation involves the
claim that the ideas and principles of reason are to be used
“regulatively,” as devices for guiding and grounding our
empirical investigations and the project of knowledge
acquisition. What the ideas do not do, according to Kant, is provide
the concepts through which we might access objects that could be known
through the speculative use of reason.

The need for this critical reinterpretation stems from the fact that
reason's demand for the unconditioned cannot be met or satisfied. The
absolutely “unconditioned,” regardless of the fact that it
presents to reason as objective, is not an object or state of affairs
that could be achieved in any possible human experience. In
emphasizing this last point, Kant identifies metaphysics with an
effort to acquire knowledge of “objects” conceived, but in
no wise given (or giveable) to us in experience. In its efforts to
bring knowledge to completion, that is, reason posits certain ideas,
the “soul,” the “world” and “God.”
Each of these ideas represents reason's efforts to think the
unconditioned in relation to various sets of objects that are
experienced by us as conditioned.

It is this general theory of reason, as a capacity to think (by means
of “ideas”) beyond all standards of sense, and as carrying
with it a unique and unavoidable demand for the unconditioned, that
frames the Kantian rejection of metaphysics. At the heart of that
rejection is the view that although reason is unavoidably motivated to
seek the unconditioned, its theoretical efforts to achieve it are
inevitably sterile. The ideas which might secure such unconditioned
knowledge lack objective reality (refer to no object), and our
misguided efforts to acquire ultimate metaphysical knowledge are led
astray by the illusion which, according to Kant, “unceasingly
mocks and torments us” (A339/B397).

As above, the Dialectic is concerned to undermine three distinct
branches of special metaphysics in the philosophical tradition:
Rational Psychology, Rational Cosmology and Rational Theology. Each of
these disciplines seeks to acquire knowledge of a particular
metaphysical “object” — the “soul,” the
“world,” and “God,” respectively. This being
stated, the Dialectic proceeds systematically to undermine the
arguments specific to each of these disciplines—arguments about,
for example, the nature of the soul and the world, and the existence
of God. Even so, there are a number of problems shared by all the
disciplines of special metaphysics, despite the difference in their
objects. In its most general terms, the central problem with each of
these attempts has to do with the fact that the alleged
“objects” under consideration are in each instance
“transcendent.” Although we think the soul, the world, and
God (necessarily) as objects, these ideas actually lack
objective reality (there is no object that corresponds to each of
these ideas that is or could be given to us in any intuition). It is
thus not uncommon to find Kant referring to these alleged metaphysical
entities as “mere thought entities,” “fictions of
the brain,” or “pseudo objects.” Although the
Dialectic does not presume to prove that such objects do not or could
not exist, Kant is committed by the strictures of his own
transcendental epistemology to the claim that the ideas of reason do
not provide us with concepts of “knowable” objects. For
this reason alone, the efforts of the metaphysicians are presumptuous,
and at the very least, an epistemological modesty precludes the
knowledge that is sought.

There are two noteworthy themes implicit in Kant's criticism of
metaphysics. First, Kant seems to offer an account and critique of the
ideas of reason specific to each discipline. In relation to this, the
theory of reason plays a role in Kant's efforts to argue against the
“hypostatization” of each of the ideas. More specifically,
Kant's criticism of the metaphysical disciplines centers on his
efforts to show that the ideas of reason (the soul, the world and
God), which are thought in accordance with the demand for the
unconditioned, get erroneously “hypostatized” by reason,
or thought as mind-independent “objects” about which we
might seek knowledge. In the same way, that is, that the prescription
to seek the unconditioned appears to reason as an objective principle,
so too, the subjective ideas appear to reason as objects existing in a
mind-independent way. Kant's aim is to secure the subjective status of
the ideas while diffusing the metaphysics that attends to them.

Thus, Kant's criticism of metaphysics simultaneously involves denying
the pure use of theoretical reason as an instrument for
knowledge of transcendent objects, and defending
reason's ideas as projections or goals that have some significant role
to play in the overall project of knowledge acquisition. As we shall
see, Kant unfortunately is not as clear as we might like on this
issue. Sometimes, he seems to argue that the ideas and principles of
reason play a merely heuristic role in guiding and systematizing the
knowledge already obtained. Other times, he suggests that these ideas
are deeply essential to the project of knowledge acquisition, and that
their presupposition is utterly necessary if we are to acquire
knowledge. Regardless of this, it is clear that Kant's criticism of
metaphysics does not entail any straightforward rejection of the ideas
and principles of reason. Indeed, it appears to be precisely the
rational constraint to move to the ideas of reason that binds us to
our metaphysical propensities and which thus demands a critique of the
kind offered by Kant.

In addition to criticizing the “hypostatization” of the
ideas of reason, Kant seeks to expose the “subreptions”
involved in the use of the ideas. The term “subreption”
refers to a fallacy that specifically involves the surreptitious
substitution of different kinds of terms and concepts. Kant
usually uses the term to refer to the error of confusing or
substituting concepts and principles meant for use in experience
(those which properly apply to appearances) with principles of
“pure reason.” By this means, a concept or principle which
is a condition of our experience (e.g., the principle of apperception)
is used in a way that assumes its applications to “objects in
general” or things in themselves. Alternatively, a most general,
formal, principle that would only hold for things in general is taken,
by itself alone, to yield knowledge about appearances. The second kind
of criticism found throughout the Dialectic thus pertains to Kant's
efforts to expose the subreptions that ground the metaphysical
attempts. Ultimately, Kant will also seek to reveal the very
specific formal fallacies that vitiate the metaphysical arguments, to
demonstrate that (although they have the appearance of soundness) the
positions in each case are implicitly grounded in, or deploy,
dialectical uses of terms and concepts, misapplications of principles,
and conflations of appearances with things in themselves. What we find
in Kant's criticism of metaphysics, in other words, is a complex
account, one grounded in a fairly robust theory of human reason.
Accordingly, he identifies reason as the locus of certain principles
and propensities, and certain “illusions,” which cooperate
with misapplications of concepts and principles to create the errors
already exposed in the Transcendental Analytic. Although this variety
of aims and complaints certainly complicates Kant's discussions in the
Dialectic, it also makes for a richer and more penetrating criticism
of metaphysics.

One historically predominant metaphysical interest has to do with
identifying the nature and the constitution of the soul. Partly for
practical reasons, partly for theoretical explanation, reason lodges
on the idea of a metaphysically simple being, the soul. Such an idea
is motivated by reason's demand for the unconditioned. Kant puts this
point in a number of ways, suggesting that the idea of the soul is one
to which we are led necessarily insofar as we are constrained by
reason to seek the “totality” of the “synthesis of
conditions of a thought in general” (A397), or insofar as we
seek to represent “the unconditioned unity” of
“subjective conditions of representations in general”
(A406/B433). More straightforwardly, Kant states that a metaphysics of
the soul is generated by the demand for the “absolute
(unconditioned) unity of the thinking subject itself”
(A334/B391). The branch of metaphysics devoted to this topic is
Rational Psychology. Rational psychologists, among whom Descartes or
Leibniz would serve as popular historical examples, seek to
demonstrate, for example, the substantiality, simplicity, and personal
identity of the soul. Each such inference, however, involves
concluding “from the transcendental concept of the subject,
which contains nothing manifold, the absolute unity of this subject
itself, of which I possess no concept whatsoever”
(A340/B398). In other words, Kant takes the rational psychologist to
slide (mistakenly) from formal features of subjectivity to material or
substantive metaphysical claims about an alleged (super-sensible)
object (the soul).

An essential aspect of all these arguments is, according to Kant,
their attempt to derive conclusions about the nature and constitution
of the “soul” a priori, simply from an analysis
of the activity of thinking. A classic example of such an attempt is
provided by Descartes, who deduced the substantiality of the self from
the proposition (or, perhaps better, the activity) “I
think.” This move is apparent in the Cartesian inference from “I
think” to the claim that the “I” is therefore “a
thing” that thinks. For Descartes, this move is unproblematic:
thought is an attribute, and thus presupposes a substance in which it
inheres. Kant emphasizes the a priori basis for the
metaphysical doctrine of the soul by claiming that in rational
psychology, the “I think” is supposed to provide the
“sole text” (A343–4/B401–02). It is this feature of the
discipline that serves to distinguish it from any empirical doctrine
of the self (any empirical psychology), and which secures its status
as a “metaphysics” that purports to provide synthetic
a priori knowledge.

Kant's criticisms of rational psychology draw on a number of distinct
sources, one of which is the Kantian doctrine of apperception. Kant
denies that the metaphysician is entitled to his substantive
conclusions on the grounds that the activity of self-consciousness
(transcendental apperception, often formulated in terms of the
necessary possibility of attaching the “I think” to all my
representations (B132)) does not yield any object for thought.
Nevertheless, reason is guided by its projecting and objectifying
propensities. In accordance with these, self-consciousness is
“hypostatized,” or objectified. Here again, Kant claims
that a “natural illusion” compels us to take the
apperceived unity of consciousness as an intuition of an object
(A402). The ineliminably subjective nature of self-consciousness, and
the elusiveness of the “I” in the context of that
activity, are thus the well known bases for Kant's response to
rational psychology, and the doctrine of apperception plays an
important role in Kant's rejection. For in each case, Kant thinks that
a feature of self-consciousness (the essentially subjectival, unitary
and identical nature of the “I” of apperception) gets
transmuted into a metaphysics of a self (as an object) that is
ostensibly “known” through reason alone to be substantial,
simple, identical, etc. This slide from the “I” of
apperception to the constitution of an object (the soul) has received
considerable attention in the secondary literature, and has fueled a
great deal of attention to the Kantian theory of mind and mental
activity.

The claim that the ‘I’ of apperception yields no object of
knowledge (for it is not itself an object, but only the
“vehicle” for any representation of objectivity as such)
is fundamental to Kant's critique of rational psychology. Kant thus
spends a considerable amount of time in the sections on the
paralogisms noting repeatedly that no object is given in
transcendental self-consciousness, and thus that the rational
psychologist's efforts to discern features of the self, construed as a
metaphysical entity, through reason alone are without merit. To
elucidate the ways in which the rational psychologist is nevertheless
seduced into making this slide from formal representations of self
consciousness to a metaphysics of the self, Kant examines each of the
psychological arguments, maintaining that all such arguments about the
soul are dialectical. He refers to the arguments designed to draw such
conclusions, “transcendental paralogisms.” A
transcendental paralogism, according to Kant, is a “syllogism in
which one is constrained, by a transcendental ground, to draw a
formally invalid conclusion” (A341/B399). Kant's subsequent
efforts are thus directed towards demonstrating the paralogistic
(fallacious) nature of the arguments about the soul.

Kant's diagnosis of the fallacies that characterize these arguments
has received considerable attention, and has generated considerable
controversy. In each case, Kant tells us, the argument is guilty of
the fallacy of sophisma figuraedictionis, or the
fallacy of equivocation/ambiguous middle. Kant suggests that in each
of the syllogisms, a term is used in different senses in the major and
minor premises. Consider the first paralogism, the argument that
allegedly deduces the substantiality of the soul. In the A edition,
Kant formulates the argument as follows:

That the representation of which is the absolute subject of our
judgments and cannot be employed as determination of any other thing,
is substance.

I, as thinking being, am the absolute subject of all my possible
judgments and this representation of myself cannot be employed as
determination of any other thing.

Therefore, I, as thinking being (soul), am substance. (A349)

Kant locates the equivocation contained in the argument in the use of
the term “substance.” According to Kant, the major premise
uses this term “transcendentally” whereas the minor
premise and conclusion use the same term “empirically.”
(A403). What Kant appears to mean is this: the major premise deploys
the term “substance” in a very general way, one which
abstracts from the conditions of our sensible intuition (space and
time). As such, the major premise simply offers the most general
definition of substance, and thus expresses the most general rule in
accordance with which objects might be able to be thought as
substances. Nevertheless, in order to apply the concept of substance
in such a way as to determine an object, the category would have to be
used empirically. Unfortunately, such an empirical use is precluded by
the fact that the alleged object to which it is being applied is not
empirical. Even more problematically, on Kant's view, there is no
object given at all. In Kantian jargon, the category only yields
knowledge of objects if it is “schematized,” applied to
given objects under the conditions of time.

This same kind of complaint is lodged against each of the paralogistic
syllogisms that characterize Rational Psychology. Thus, Kant argues
against the inference to the simplicity of the soul, by remarking that
the psychologist here is surreptitiously deducing the actual
simplicity of a metaphysical object simply from the formal features of
subjectivity (the fact that the “I” is unitary in our
representational economy). The personal identity of the soul is
attacked on similar grounds. In each case the metaphysical conclusion
is said to be drawn only by an equivocation in the use or meaning of a
concept of the understanding.

This illustrates Kant's efforts to demonstrate the fallacious nature
of the arguments that characterize metaphysics, as well as his
interest in identifying the sources of such errors. Given this, Kant's
criticisms of rational psychology are not as straightforward as one
might expect, for embedded in his criticisms of rational psychology
are actually a number of distinct charges: 1) The idea of the soul,
although it is one to which we are naturally led in our quest for the
unconditioned ground of thought, does not correspond to any object
that is (or could be) actually given to us in intuition. The
hypostatization of this idea, therefore, although it may be natural,
is deeply problematic. 2) Because the idea of the soul does not yield,
by itself alone, any knowable object, the arguments about it, although
they may have the appearance of being legitimate, in fact involve
dialectical applications of concepts. The arguments, in other words,
involve fallacies that vitiate their conclusions. 3) The arguments are
traceable back to certain features of human reason that may not be
eradicated, but that can and ought to be curbed and critically
reinterpreted. More specifically, the demand for the unconditioned,
and the idea of the soul to which it gives rise, may be construed
regulatively as devices for guiding inquiries, but never constitutively
— never, that is, as yielding grounds for any a priori synthetic
knowledge of a metaphysical self given immediately to pure reason.

The second discipline of rationalist metaphysics rejected by Kant is
Rational Cosmology. Rational cosmology is concerned with the arguments
about the nature and constitution of the “world,”
understood as the sum-total of all appearances (objects and events in
space and time) (A420/B448). The arguments about the world occupy an
especially important place in Kant's rejection of metaphysics. Not
only does Kant address himself to the task of discounting the
metaphysical arguments in cosmology, but the resolution to some of
these conflicts provides, he claims, an indirect argument for his own
transcendental idealism.

The arguments about the world are referred to by Kant as
“antinomies” because in the field of cosmology, reason
gives rise to sets of opposing arguments (the “thesis” and
the “antithesis”) with respect to each issue. Thus, the
case here differs from the paralogisms (and, as we shall see, from the
Ideal). The reason for this difference resides in the nature of the
idea of reason in question. More specifically, the idea of the
“world” purports to be an idea of an unconditioned but
somehow still sensible object (cf. A479/B509). Unlike the soul, which
is clearly supposed to be a metaphysical entity that is not sensible,
for example, the sum total of all appearances refers specifically to
spatio-temporal objects or events. Kant highlights this unique feature
of the idea of the world by noting that whereas the ideas of the soul
and God are “pseudo-rational,” the idea of the world is
“pseudo-empirical.” It is precisely this feature of the
idea (that it both purports to refer to a somehow sensible object AND
that it involves thinking that object as already given in its
totality) that leads to the two opposed sets of arguments. For with
respect to each problem addressed (the finitude vs. the infinitude of
the world, freedom vs. causality, etc.), one can either adopt a
broadly “dogmatic” (Platonic) or broadly
“empiricist” (Epicurean) approach, each reflecting a
different way of thinking the totality of conditions (See
A471–2/B499–500). More specifically, one can either think the
unconditioned as an intelligible ground of appearances, or as the
total (even if infinite) set of all appearances. The problem is that
each of these conceptual strategies is unsatisfying. To accommodate
the thesis interest in ultimate (intelligible) beginnings is to posit
something “too big” for the understanding, something that
is never to be met with empirically (e.g., freedom, ultimately simple
substances). Thus, although the thesis positions satisfy reason's
demand for the unconditioned, they do so by fleeing (however
unwittingly) into an intelligible realm, by providing explanations
that abstract from that which is or could be given in any
spatio-temporal experience.

Adopting the empiricist approach is no more rewarding, in the final
analysis; although the antithesis positions remain securely lodged
within “nature's own resources,” they can never measure up
to the demands of reason's ideas. Worse, the antithesis arguments, in
refusing to go beyond the spatio-temporal realm, end up being just as
dogmatic as their opposites, for the assumption is that whatever holds
within space and time also holds generally. To assume this is to take
what are for Kant merely subjective features of our intuition (forms
of sensibility, space and time) to be universal ontological conditions
holding of everything whatsoever. Such a strategy is “too
small” for reason which, even despite the limits of our own
human sensibility, is defined by its capacity to think beyond all
standards of sense and by its demand for more thorough
explanation.

Because both sides to the cosmological disputes seem to be able to
argue successfully against the opposite, Kant finds in the antinomies
a dramatic exhibition of the “conflict” into which reason
inevitably falls (and in which it will remain) so long as it fails to
adopt his own transcendental distinction between appearances and
things in themselves. The historical debacle of reason's conflict with
itself provides Kant with a dramatic exhibition of the vacillation of
reason between two alternatives, neither of which it can accept (or
dismiss) without dissatisfaction. Left unresolved, this conflict is
disastrous in that it leads to the “euthanasia of pure
reason” (A407/B434).

There are four “antinomies” of pure reason, and Kant
divides them into two classes. The first two antinomies are dubbed
“mathematical” antinomies, presumably because in each
case, we are concerned with the relation between what are alleged to
be sensible objects (either the world itself, or objects in it) and
space and time. An important and fundamental aspect of Kant's
rejection of each of these sets of arguments rests on his view that
each of these conflicts is traceable back to a fundamental error, an
error that can be discerned, according to Kant, in the following
dialectical syllogism:

If the conditioned is given, then the whole series of conditions, a
series which is therefore itself absolutely unconditioned, is also
given

Objects of the senses are given as conditioned

Consequently, the entire series of all conditions of objects of the
senses is already given. (cf. A497/B525).

There are a number of problems with this argument, according to
Kant. Obviously, one problem is located in the major premise, in the
assumption that the unconditioned is “already given.” The
problem, maintains Kant, is that such a totality is never to be met
with in experience. The rational assumption that the total series of
all conditions is already given would hold only for things in
themselves. In the realm of appearances, the totality is never given
to us, as finite discursive knowers. The most we are entitled to say,
with respect to appearances, is that the unconditioned is set as a
task, that there is a rational prescription to continue to seek
explanations (A498/B526-A500/B528). As finite (sensible) cognizers,
however, we shall never achieve an absolute completion of
knowledge. To assume that we can do so is to adopt the theocentric
model of knowledge characteristic of the dreaded transcendental
realist.

Given this, problems stem from the application of the principle
expressed in the first premise to the objects of the senses
(appearances). Here again, Kant diagnoses the error or fallacy
contained in this syllogism as that of ambiguous middle. He
claims that the major premise uses the term “the
conditioned” transcendentally, as a pure concept, whereas the
minor premise uses the term “empirically”—that is as
a “concept of the understanding applied to mere
appearances” (cf. A499–500/B527–528). What Kant means here is
that the major premise uses the term “the conditioned” in
a very general way, one that considers things in abstraction from the
sensible conditions of our intuition. The minor premise, however,
which specifically refers to objects in space and time (appearances),
is committed to an empirical use of the term. Indeed, such an
empirical use would have to be deployed, if the conclusion is to be
reached. The conclusion is that the entire series of all conditions of
appearances is actually given. Put in other terms, the
conclusion is that there is a world, understood as the sum
total of all appearances and their conditions (A420/B448).

This hypostatization of the idea of the world, the fact that it is
taken to be a mind-independent object, acts as the underlying
assumption motivating both parties to the two mathematical antinomies.
The first antinomy concerns the finitude or infinitude of the
spatio-temporal world. The thesis argument seeks to show that the
world in space and time is finite, i.e., has a beginning in time and a
limit in space. The antithesis counters that it is infinite with
regard to both space and time. The second antinomy concerns the
ultimate constitution of objects in the world, with the thesis arguing
for ultimately simple substances, while the antithesis argues that
objects are infinitely divisible. In this, the thesis positions are
each concerned to bring the explanatory effort to a close, by arguing
for ultimate or, as Kant says, “intelligible beginnings”
(cf. A466/B494). The claim that there is a “first
beginning” or an ultimately simple substance is sustained only
by abstracting from the spatio-temporal framework. The alleged
proponent of the antithesis arguments, on the other hand, refuses any
conclusion that goes beyond the sensible conditions of space and
time. According to the antithesis arguments, the world is infinite in
both space and time (these being infinite as well), and bodies are (in
accordance with the infinite divisibility of space) also infinitely
divisible.

In each of these antinomial conflicts, reason finds itself at an
impasse. Satisfying the demands placed by our rational capacity to
think beyond experience, the thesis arguments offer what appears to be
a satisfying resting-place for explanation. The antithesis charges
that such a strategy fails to find any confirmation, and, citing the
unjustified flight into an intelligible realm, lodges itself squarely
in the domain of “experience.” In each of these cases, the
conflicts are resolved by demonstrating that the conclusions drawn on
both sides are false.

How does Kant demonstrate this? Both the thesis and antithesis
arguments are apagogic, i.e., that they constitute indirect proofs. An
indirect proof establishes its conclusion by showing the impossibility
of its opposite. Thus, for example, we may want to know, as in the
first antinomy, whether the world is finite or infinite. We can seek
to show that it is finite by demonstrating the impossibility of its
infinitude. Alternatively, we may demonstrate the infinitude of the
world by showing that it is impossible that it is finite. This is
exactly what the thesis and antithesis arguments purport to do,
respectively. The same strategy is deployed in the second antinomy,
where the proponent of the thesis position argues for the necessity of
some ultimately simple substance by showing the impossibility of
infinite divisibility of substance, etc.

Obviously, the success of the proofs depends on the legitimacy of the
exclusive disjunction agreed to by both parties. Both parties, that
is, assume that “there is a world,” and that it is, for
example, “either finite or infinite.” Herein lies the
problem, according to Kant. The world is, for Kant, neither finite nor
infinite. The opposition between these two alternatives is merely
dialectical.

In the dynamical antinomies, Kant changes his strategy somewhat.
Rather than arguing (as in the mathematical antinomies) that both
conclusions are false, Kant suggests that both sides to the
dispute might turn out to be correct. This option is available here,
and not in the two mathematical antinomies, because the proponents of
the thesis arguments are not committing themselves solely to claims
about spatio-temporal objects. In the third antinomy, the thesis
contends that in addition to mechanistic causality, we must posit some
first uncaused causal power (Transcendental Freedom), while the
antithesis denies anything but mechanistic causality. Here, then, the
debate is the standard (though in this case, the specifically
cosmological) dispute between freedom and determinism. Finally, in the
fourth antinomy, the requirement for a necessary being is pitted
against its opposite. The thesis position argues for a necessary
being, whereas the antithesis denies that there is any such being.

In both cases the thesis opts for a position that is abstracted from
the spatio-temporal framework, and thus adopts the broadly Platonic
view. The postulation of freedom amounts to the postulation of a
non-temporal cause, a causality outside the series of appearances in
space and time (A451/B479). Similarly, in its efforts to argue for a
“necessary being,” reason is forced (against its own
argument) into a non-sensible realm. If there is a necessary being, it
will have to be “outside” the series of appearances:
“Either, therefore, reason through its demand for the
unconditioned must remain in conflict with itself, or this
unconditioned must be posited outside the series, in the
intelligible” (A564/B592). The rational necessity of postulating
such a necessary being or a causality of freedom satisfies the
rational demand for intelligible explanation. Against this, the
antithesis rightly notes that the conception of transcendental
freedom, or a necessary being, again represents an attempt to abstract
from “nature's own resources” (A451–2/B479–80). Insofar as
the antithesis denies the justification for doing this, of course, it
is said to adopt a broadly Epicurean standpoint. The problem here,
however, is that in refusing to move beyond “nature's own
resources,” the antithesis surreptitiously smuggles in
spatio-temporal conditions as the basis for a universal ontological
claim that nevertheless transcends all experience. If space and time
were things in themselves, then of course the application of the
demand for this unconditioned would be warranted. Kant's view,
however, is that space and time are not conditions of things in
themselves.

The resolution to these antinomies here consists in giving each side
its due, but simultaneously limiting the domain over which the claims
hold. The thesis demand for an absolute causal beginning or a
necessary being might well be allowed to stand, but certainly not as
“part of” or as an explication of appearances in
nature. Similarly, the antithesis conclusions can stand, but only in
relation to objects in nature, considered as appearances. Here, the
conflict seems irresolvable only on the assumption that appearances
are things in themselves. If appearances were things in themselves,
for example, then it would certainly seem true that either they are
one and all subject to mechanistic causality, or not. In such a case,
it makes sense both to argue for a non-temporal beginning and to deny
such a beginning. Left unresolved, then, this antinomy leaves us wit
the following dilemma: on the assumption of transcendental realism,
both nature and freedom seem to be undermined. To avoid this, Kant
appeals to transcendental idealism, which is supposed to rescue reason
from the conflict. Given transcendental idealism (with its distinction
between appearances and things in themselves) it remains possible that
in addition to the mechanism of nature, or contingent existence, there
is an intelligible causal power, or a necessary being.

The metaphysical drive, and the demand for the unconditioned, seem to
find their natural resting place in the idea of God, an absolutely
necessary and supremely real being, the concept of which
“contains a therefore for every wherefore” (A585/B613). It
is here, in the concept of God, that the demands for systematic unity
and completeness of knowledge find their “objective
correlate.” Kant refers to this idea as an Ideal, suggesting it
defines itself as a “concept of an individual object which is
completely determined through the mere idea” (A574/B602). The
Ideal represents the highest singular manifestation of reason's demand
for the unconditioned.

The last area of metaphysics under attack, then, is Rational
Theology. Kant's criticism of rational theology is complicated by his
desire to elucidate the sources of the dialectical errors,
which he will expose in relation to the specific arguments for God's
existence. (“…Merely to describe the procedure of our
reason and its dialectic does not suffice; we must also endeavor to
discover the sources of this dialectic, that we may explain…the
illusion to which it has given rise” (A581/B607).) Kant thus
spends a considerable amount of time tracing the idea of God back to
its rational, speculative, sources. According to Kant,
“….the Ideal …is based on a natural, not a merely
arbitrary idea” (A581/B607). On this score, Kant wants to tell
us that we are compelled to think the idea of God (the ens
realissimum) when pursuing certain speculative or philosophical
interests. More specifically, the idea of a supremely real being (the
ens realissimum) is one to which we are inevitably led during
our attempts to account for the pure possibility of things in general.
The upshot that the idea of the ens realissimum is not an
arbitrary or easily dispensable one. Instead, Kant suggests that
reason is philosophically constrained to move to such an idea in its
efforts to thoroughly determine every thing. Such efforts require
thinking the totality, or “All” of reality (the
omnitudo realitatis). Such an idea is philosophically
required because, in our efforts to thoroughly determine each thing
(to know it completely, specify it exhaustively), we must be able to
say, of every possible predicate and its contradictory (p v
˜p) which of the two holds of the thing in
question. (For every object, it is either A or not
A, either B or not B, etc., and this
process is iterated until each predicate pair (each positive reality)
is exhausted — Kant clearly has a Leibnizian procedure of
complete determination in mind here.) This process is parasitic upon
the idea of “sum total of all predicates of things in
general.” Or, put in another way, we represent “every
thing as deriving its own possibility from the share it has in the
whole of possibility” (A572/B600). Such an idea, the All of
reality, however, defines itself as an individual thing, and leads us
to the representation of the “supremely real being.” The
problem seems to come in, according to Kant, when the
“All” of reality gets hypostatized, and (eventually)
personified, thus yielding the ens realissimum (cf.
A583/B611n). Here again, Kant thinks that this idea itself gets
transmuted into the notion of a given object by virtue of a unique
subreption, whereby we dialectically substitute for a principle that
is only meant for empirical employment one which holds of things in
general. The argument Kant offers is excruciating, but the essential
point is that, just as the idea of the soul involved the subreption of
the hypostatized consciousness, so too, the idea of the ens
realissimum is generated by both a subrepted principle and a
hypostatization.

As in the cases of both rational psychology and rational cosmology,
then, one central problem thus has to do with the assumption that pure
(speculative) reason yields any access to a transcendent object (in
this case, God) about which it is entitled to seek a priori
knowledge. Despite his insistence that the idea of God is
indispensable and “inescapable” (cf. A584/B612), Kant
again denies that we can acquire any theoretical knowledge of the
alleged “object” thought through such an idea. On the one
hand, then, the idea of God is “the crown of our
endeavors.” On the other, as in the cases of both rational
psychology and cosmology, the idea answers to no given and
theoretically knowable object (A339/B397). Indeed, according to Kant,
the idea of God should not lead us to “presuppose the existence
of a being that corresponds to this ideal, but only the idea of such a
being, and this only for the purpose of deriving from an unconditioned
totality of complete determination the
condition…” (A578/B606). As in the other disciplines of
metaphysics, Kant suggests that we are motivated (perhaps even
constrained) to represent the idea as a real object, to hypostatize
it, in accordance the demand for the unconditioned:

Notwithstanding this pressing need of reason to presuppose
something that may afford the understanding a sufficient foundation
for the complete determination of its concepts, it is yet too easily
conscious of the ideal and merely fictitious character of such a
presuppostion to allow itself, on this ground alone, to be persuaded
that a mere creature of its own thought is a real being — were
it not that it is impelled from another direction to seek a resting
place in the regress from the conditioned, which is given, to the
unconditioned (A584/B612)

This demand for the unconditioned, according to Kant, links up with a
demand for some ultimately necessary being. Reason, that is,
ceaselessly demands the ground of all the contingent beings in
existence, and will not rest until it settles on the absolutely
necessary being which grounds them. The idea of the ens
realissimum plays a singular role in satisfying this desire of
reason, for of all concepts, it is that “which best squares with
the concept of an unconditionally necessary being” (A586/B614).
In fact, according to Kant rational theology is based on the
coincidence of the rational demands for a supremely real being and for
a being with absolutely necessary existence. If the movement to the
idea of God, as the unconditioned ground, is inevitable, it is
nevertheless as troublesome as the other rational ideas:

This unconditioned is not, indeed, given as being in
itself real, nor as having a reality that follows from its mere
concept; it is, however, what alone can complete the series of
conditions when we proceed to trace these conditions to their
grounds. This is the course which our human reason, by its very
nature, leads all of us (A584/B612; cf. A584/B612n).

Thus, although Kant is most well known for his attacks on the specific
arguments for God's existence, his criticisms of rational theology are
in fact more detailed, and involve a robust critique of the idea of
God itself. This account of the rational origin and the importance of
the idea of God clears the way for Kant's rejection of the
metaphysical arguments about God's existence. Kant identifies three
traditional arguments, the ontological, the cosmological, and the
physico-theological (the argument from design). What all such
arguments do is attempt to wed the idea of the ens
realissimum with the notion of necessary existence. Whereas the
Ontological argument moves from the concept of the ens
realissimumto the claim that such a being exists
necessarily, the Cosmological and physico-theological arguments move
from some necessary being to the conclusion that such a being
must be the ens realissimum.

Kant's formulation of the ontological argument is fairly
straightforward, and may be summarized as follows:

God, the ens realissimum, is the concept of a being that
contains all reality/predicates.

Existence is a reality/predicate.

Therefore God exists.

Kant's identification of the errors involved in this argument are so
varied that it seems surprising that he is so often simply said to
have argued against the use of “existence” as a
predicate. His first complaint is that it is
“contradictory” insofar as it introduces
“existence” into the “concept of a thing which we
profess to be thinking solely in reference to its possibility”
(A597/B625). This suggests that he thinks that in taking “all
reality” to mean or include “existence,” the
rational theologist begs the question, and already posits the analytic
connection between the concept of the ens realissimum and
necessary existence.

At the heart of this complaint is a more general one, to wit, that
there is a problem with the attempt to infer anything as
necessarily existing. Although, according to Kant, reason is
unavoidably led to the notion of an absolutely necessary being, the
understanding is in no position to identify any candidate answering to
the idea. (cf. A592/B620). Clearly, the ontological argument is
designed to show that, in fact, there is one (and only one)
candidate answering to this idea, namely, the ens
realissimum. But it does so by deducing the necessary existence
from the concept of the ens realissimum (a being that
contains all reality or predicates) only via the minor premise that
“existence” is a predicate or reality. Kant, however,
famously denies that existence is a “real predicate,” or
determination. Thus, one criticism is that the argument conflates
merely logical with real (determining) predicates. A real
(determining) predicate is one that enlarges the concept to which it
is attached. It seems clear that the locus of the error here, as in
the other metaphysical disciplines, is the view that the idea of the
ens realissimum provides us with a concept of an
“object” to which it would be appropriate to apply
categories or concepts in a determining way. Thus, included in Kant's
criticism is the claim that the category of existence is being subject
to a transcendental misemployment (A598/B626). This misapplication of
the category is problematic precisely because, according to Kant, we
are dealing only with an object of pure thought, whose existence
cannot be known (A602/B630).

If the ontological argument seeks to move from the concept of the
ens realissimum to the concept of an absolutely necessary
being, both the cosmological and physicotheological proofs move in the
opposite direction. Each, that is, argues that there is something that
must exist with absolute necessity and concludes that this being is
the ens realissimum. Because these proofs aim to identify the
ens realissimum with the necessary being, and because the
attempt to do this requires an a priori argument (it cannot
be demonstrated empirically), Kant thinks that they are both
(ultimately) vitiated by their reliance on the ontological
proof. More specifically, they are both mitigated by their assumption
that the ens realissimum is the only object or candidate that
can do the job of existing necessarily. Since he thinks that the
ontological argument is in some sense implicitly relied upon in making
such a claim, these arguments stand or fall with it. On Kant's view,
as we shall see, they fall.

The cosmological proof has, according to Kant, two parts. As
above, the proponent of the argument first seeks to demonstrate the
existence of an absolutely necessary being. Second, the rational
cosmologist seeks to show that this absolutely necessary being is the
ens realissimum.

As Kant formulates it, the cosmological argument is as follows:

If something exists, then an absolutely necessary being must also
exist.

I myself, at least, exist.

Therefore an absolutely necessary being exists.

As above, the theist will ultimately want to identify this necessary
being with the ens realissimum, an identification which Kant
thinks surreptitiously smuggles in the (dialectical) ontological
argument. The claim here is that the proponent of the cosmological
argument is committed ultimately to accepting the ontological
argument, given her attempt to identify the necessary being with the
ens realissimum. Although this suggests that the cosmological
argument relies on the ontological, Kant also indicates that the
effort to produce a purely a priori argument for God's
existence (the ontological argument) itself gets momentum from
reason's need to find the necessary ground for existence in general, a
need expressed in the cosmological argument
(cf. A603–04/B631–32). This suggests that Kant takes the ontological
and cosmological arguments to be complementary expressions of the one
underlying rational demand for the unconditioned.

Even aside from its alleged commitment to the ontological argument,
Kant has a number of complaints about the cosmological argument.
Indeed, according to Kant, the cosmological argument is characterized
by an “entire nest of dialectical presumptions” which must
be illuminated and “destroyed” (A609/B637). These
dialectical presumptions include the attempt to infer from the
contingent (within experience) to some cause lying outside the world
of sense altogether, an effort involving a transcendental
misapplication of the categories. It also includes, Kant claims, the
dialectical effort to infer from the conceptual impossibility
of an infinite series of causes to some actual first cause
outside of sense. Such efforts involve a “false
self-satisfaction” according to which reason feels itself to
have finally landed on a truly necessary being. Unfortunately,
according to Kant, this is only achieved by conflating the merely
logical possibility of a concept (that it is not
self-contradictory) with the transcendental (real)
possibility of a thing. In short, the cosmological argument
gets its momentum by confusing rational or subjective necessities with
real or objective ones, and thus involves transcendental illusion
(cf. A605/B633).

We come finally to the physicotheological proof, which argues
from the particular constitution of the world, specifically its
beauty, order, and purposiveness, to the necessary existence of an
intelligent cause (God). Such an argument goes beyond the cosmological
one by moving not from existence in general but from some
determinate experience in order to demonstrate the existence
of God (A621/B649). Although this might seem to be a strength, this
strategy is doomed to fail, according to Kant. No experience could
ever be adequate to the idea of a necessary, original being:
“The transcendental idea of a necessary all-sufficient original
being is so overwhelmingly great, so sublimely high above everything
empirical, which is at all times conditioned, that partly one can
never even procure enough material in experience to fill such a
concept, and partly if one searches for the unconditioned among
conditioned things, then one will seek forever and always in
vain” (A621/B649).

Kant's claim is that even if we could grant that the order and
purposiveness of nature gives us good reason to suppose some
intelligent designer, it does not warrant the inference to an ens
realissimum. At most, Kant tells us, the proof could establish a
“highest architect of the world…., but not a creator of
the world.” (A627/B655). The last inference, that to the ens
realissimum, is only drawn by moving far away from any
consideration of the actual (empirical) world. In other words, here
too, Kant thinks that the rational theologist is relying on a
transcendental (a priori) argument. Indeed, according to
Kant, the physicotheological proof could never, given its empirical
starting point, establish the existence of a highest being by itself
alone, and must rely on the ontological argument at crucial stages
(cf. A625/B653). Since, according to Kant, the ontological argument
fails, so does the physicotheological one.

Although Kant rejects the physiciotheological argument as a
theoretical proof for God's existence, he also sees in it a powerful
expression of reason's need to recognize in nature purposive unity and
design (cf. A625/B651). In this, the physicotheological argument's
emphasis on the purposiveness and systematic unity of nature
illuminates an assumption that Kant takes to be essential to our
endeavors in the natural sciences. The essential role played by the
assumption of purposive and systematic unity, and the role it plays in
scientific inquiries, is taken up by Kant in the Appendix to the
Transcendental Dialectic. To this topic we now turn.

The criticisms of the metaphysical arguments offered in the
Transcendental Dialectic do not bring Kant's discussion to a close.
Indeed, in an “Appendix” to the Transcendental Dialectic,
Kant returns to the issue of reason's positive or necessary role. The
curious “Appendix” has provoked a great deal of confusion,
and not without reason. After all, the entire thrust of the Dialectic
seemed to be directed at “critiquing” and curbing pure
reason, and undermining its pretense to any real use. Nevertheless,
Kant goes on to suggest that the very reason that led us into
metaphysical error is also the source of certain necessary ideas and
principles, and moreover, that these rational postulations play an
essential role in scientific theorizing (A645/B673;
A671/B699). Exactly what role they are supposed to play in this regard
is less clear.

The Appendix to the Transcendental Dialectic is divided into two
parts. In the first, “On the Regulative Use of the Ideas of Pure
Reason,” Kant attempts to identify some proper
“immanent” use for reason. In its most general terms, Kant
is here concerned to establish a necessary role for reason's principle
of systematic unity. This principle was first formulated by Kant in
the Introduction to the Transcendental Dialectic in two forms, one
prescriptive, and the other in what sounded to be a metaphysical
claim. In the first, prescriptive form, the principle enjoins us to
“Find for the conditioned knowledge given through the
understanding the unconditioned whereby its unity is brought to
completion.” The complementary metaphysical principle assures us
that the “unconditioned” is indeed given and there to be
found. Taken together, these principles express reason's interests in
securing systematic unity of knowledge and bringing such knowledge to
completion.

Kant is quite clear that he takes reason's demand for systematicity to
play an important role in empirical inquiry. In connection with this,
Kant suggests that the coherent operation of the understanding somehow
requires reason's guiding influence, particularly if we are to unify
the knowledge given through the real use of the understanding into
scientific theory (cf. A651–52/B679–80). To order knowledge
systematically, for Kant, means to subsume or unify it under fewer and
fewer principles in light of the idea of one “whole of
knowledge” so that its parts are exhibited in their necessary
connections (cf. 646/B674). The idea of the form of a whole of
knowledge is thus said to postulate “complete unity in the
knowledge obtained by the understanding, by which this knowledge is to
be not a mere contingent aggregate, but a system connected according
to necessary laws” (A646/B676). Having said this, it should be
noted that Kant's position is, in its details, difficult to pin down.
Sometimes Kant suggests merely that we ought to seek
systematic unity of knowledge, and this merely for own theoretical
convenience (A771/B799-A772/B800). Other times, however, he suggests
that we must assume that the nature itself conforms to our
demands for systematic unity, and this necessarily, if we are to
secure even an empirical criterion of truth (cf. A651–53/B679–81). The
precise status of the demand for systematicity is therefore somewhat
controversial.

Regardless of these more subtle textual issues Kant remains committed
to the view that reason's proper use is always only
“regulative” and never constitutive. The distinction
between the regulative and the constitutive may be viewed as
describing two different ways in which the claims of reason may be
interpreted. A principle of reason is constitutive, according to Kant,
when it is taken to supply a concept of a real object (A306/B363;
A648/B676). Throughout the Dialectic Kant argued against this
(constitutive) interpretation of the ideas and principles of reason,
claiming that reason so far transcends possible experience that there
is nothing in experience that corresponds with its ideas. Although
Kant denies that reason is constitutive he nevertheless, as we have
seen, insists that it has an “indispensably necessary”
regulative use. In accordance with reason's demand, the understanding
is guided and led to secure systematic unity and completion of
knowledge. In other words, Kant seeks to show that reason's demand for
systematic unity is related to the project of empirical knowledge
acquisition. Indeed, Kant links the demand for systematicity up with
three other principles — those of homogeneity, specification and
affinity — which he thinks express the fundamental presumptions
that guide us in theory formation. The essential point seems to be
that the development and expansion of empirical knowledge is always,
as it were, “already” guided by the rational interests in
securing unity and completion of knowledge. Without such a guiding
agenda, and without the assumption that nature conforms to our
rational demands for securing unity and coherence of knowledge, our
scientific pursuits would lack orientation. Thus, the claim that
reason's principles play a necessary “regulative” role in
science reflects Kant's critical reinterpretation of the traditional
rationalist ideal of arriving at complete knowledge.

It is connection with this that Kant argues, in the second part of the
Appendix (“On the Final Aim of the Natural Dialectic of Human
Reason” (A669/B697)), that the three highest ideas of reason
have an important theoretical function. More specifically, in
this section Kant turns from a general discussion of the important
(regulative) use of the principle of systematicity, to a consideration
of the three transcendental ideas (the Soul, the World, and God) at
issue in the Dialectic. As examples of the unifying and guiding role
of reason's ideas, Kant had earlier appealed to the ideas of
“pure earth” and “pure air” in Chemistry, or
the idea of a “fundamental power” in psychological
investigations (cf. A650/B678). His suggestion earlier was that these
ideas are implicit in the practices governing scientific
classification, and enjoin us to seek explanatory connections between
disparate phenomena. As such, reason's postulations serve to provide
an orienting point towards which our explanations strive, and in
accordance with which our theories progressively achieve systematic
interconnection and unity. Similarly, Kant now suggests that each of
the three transcendental ideas of reason at issue in the Dialectic
serves as an imaginary point (focus imaginarius) towards
which our investigations hypothetically converge. More specifically,
he suggests that the idea of the soul serves to guide our empirical
investigations in psychology, the idea of the world grounds physics,
and the idea of God grounds the unification of these two branches of
natural science into one unified Science (cf.
A684/B712-A686/B714). In each of these cases, Kant claims, the idea
allows us to represent (problematically) the systematic unity towards
which we aspire and which we presuppose in empirical studies. In
accordance with the idea of God, for example, we “consider every
connection in the world according to principles [Principien]
of a systematic unity, hence as if they had all
arisen from one single all-encompassing being, as supreme and
all-sufficient cause” (A686/B714). Such a claim, controversial
as it is, illuminates Kant's view that empirical inquiries are one and
all undertaken in light of the rational goal of a single unified body
of knowledge. It also points towards the Kantian view, later
emphasized in the Transcendental Doctrine of Method, that reason's
theoretical and practical interests ultimately form a higher
unity.

The SEP would like to congratulate the National Endowment for the Humanities on its 50th anniversary and express our indebtedness for the five generous grants it awarded our project from 1997 to 2007.
Readers who have benefited from the SEP are encouraged to examine the NEH’s anniversary page and, if inspired to do so, send a testimonial to neh50@neh.gov.